Laura multiplied 4/13 times 3 and got 12/39. Was her answer correct?

A: no, she should have multiplied only the numerator by the whole number.
B: no, she should have multiplied only the denominator by the whole number.
C: her answer was correct, but she did not write it in simplest form.
D: yes, her answer was correct.

The correct answer is A: no, she should have multiplied only the numerator by the whole number.